A comparison study on the R-curve behavior of alumina/aluminum titanate composites prepared with different TiO2 powders

Rising crack growth resistance (R-curve) behavior of nano and micro alumina/20 wt.% aluminum titanate composites have been compared. Preparation of the composites was made using reaction sintering of the alumina and titania powders. Nano and micro sized TiO2 powders were used in achieving the Al2TiO5 as secondary phase. The toughness curves of the composites were determined using indentation-fracture method. Both of the micro and nano composites show a significant rising of toughness in comparison with the monolithic alumina. The K1C value increased from the initial value of 2.6 MPa √m to 4.5, 5.1 and 5.5 MPa √m at the maximum load (P) for alumina, micro and nano composites, respectively. The microstructural observations demonstrated that the bridging and microcracking are the main toughening mechanisms in the alumina/aluminium titanate composites. Bridging mechanisms in the micro and microcracking phenomenon in the nano composites have the major responsibility of the R-curve behavior.